Originally Posted by orangeflash05

No because that water crossover pipe...

Originally Posted by Raylar Engineering

Hi xx_ED_xx,

You need to dyno that thing! Your truck is running our stage 3 kit and a single turbo right? (206 cam / heads / roller rockers / forged bottom end)

Thank you for the compliment on the new site! We've put in a lot of time to try and explain things better than we have in the past. We want to be as informative as possible and are using questions from the forums to further answer questions and concerns that come up from customers.



As you already know, the stock manifold really chokes the motor back above 4,250 RPM. Above is a rear wheel power comparison between three of our parts combinations:
Bone Stock (grey / black)
Heads / 202 Cam / Stock Manifold (dark blue dotted / light blue dotted)
Heads / 202 Cam / Cool Gap Manifold (dark blue solid / light blue solid)
Heads / 203 Cam / Stock Manifold (maroon / red)

As you can see, the Cool Gap / 202 cam combo makes more torque and nearly the same horsepower as the 203 cam / stock manifold past 4700! While maximum power increases over the 202 cam with the 203 camshaft, it really illustrates how much airflow becomes a limiting factor with these engines.

We haven't had a chance to put a ported intake manifold on the flow bench, but the porting essentially removes all restriction making the manifolds only real restriction the 78mm throttle body.

We're estimating that the ported manifolds produce about 80% of the air flow that the Cool Gap manifold produces. Preliminary dyno results from customers who have run the ported stock Vortec manifolds show great improvements over the stock manifold with slightly higher peak power points (200-400rpm increase) and extended power bands, but not quite as much as the Cool Gap manifold extends the power band. When we have more customer dyno results we will add that information to our charts, but the ported manifold has only been available for about 2 months.

We'll be putting the ported intake manifold on our newest shop project - a 2500 Suburban with hand ported iron heads, 203 cam and a 547cid stroker kit that fits in the stock block. (We'll toss some Raylar heads and the 206 camshaft into it eventually.) We expect that the stroker kit will show the limitations of the ported stock manifold. Since I'm mentioning the soon to be available 4.75 stroker crank setup, here are some pictures of the minor block notching thats required to make it fit.





Have I interested you in tearing your motor apart yet?